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11 Cards in this Set
- Front
- Back
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How does TB mycobacterium tuberculosis work?
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It primarily infects lung Mφ leading to pathogenesis of TB.
- it can continue to persist regardless of immunity |
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Describe the microbiology of mycobacterium tuberculosis...(include characteristics and enzymes it produces....
What is its #1 virulence factor? |
- Acid fast, lowestein jenson stain, no exotoxins, UV & heat sensitive, grows very slowly produce lipoarabinomannan, catalase, peroxidase
Virulence factors- 1. cell wall composed of cord factor, mycolic acid, and wax D which allows it ability to survive within macrophages |
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How is TB transmitted?
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person to person or consumption of contaminated raw milk, and respiratory droplets
- able to survive up to 8 months |
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What are the two main clinical manifestations of tuberculosis
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1. primary- not infections 3-4 weeks after exposure (asymptomatic to flu-like symptoms), neg- xray, positive PPD
2. Reactivation TB (secondary tuberculosis)- M. tuberculosis within granulomas or tubercules of lungs multiply and divde- chronic cough that is greenish sputum or bloody, anorexia, chest pain, night sweats and gradual wasting of body |
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Describe the PPD skin test?
What does it mean if it is ... a. > 5mm b. > 10 mm c. >15 mm |
Type IV hypersensitivity reaction test used to identify infected persons often shows false positives in areas of high rates of vaccination
(Purified protein derivative) is injected into skin and examined 48-72 hrs later for induration a. positive for close contact to an infectious case, persons with abnormal chest x-ray, or person with HIV b. other medical risks, alcoholics, IV drug users, c. positive for persons without risk factors for TB |
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How is TB diagnosed?
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combination of hx, physical, mantoux tuberculin skin test, chest-xray, bacterioogic exam, sputum smear culture
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How would a microbiologist identify TB?
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- respiratory specimens with AFB smears (acid fast bacillus).
- culture for drug resistabilities - molecular methods: DNA fingerprinting, nucleic acid |
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Describe the role of TLR2 in recognition of Mycobacterium
What role does the TLR2/TLR1 have on vitamin D? |
TLR2 recognizes glycolipid LAM (lipoarabinomannan) from mycobacterium.
This leads to NFkB activation which sends signals out to activate inflammatory cytokines and antimicrobial activity TLR2/1 activation results in induction of key genes in vitamin D pathway, relating UV intake (which increases vit D) to control of TB |
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How does Vit D increases help control TB?
Why are black people more susceptible to TB? |
Vitamin D pathway makes antimicrobial peptide cathelicidin which has direct action against intracellular Mycobacterium tuberculosis
Black people have low serum vitamin D prohormone levels |
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What do CD8 Tcells do to fight mtb?
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CD8+ T cells- IFN-γ and TNF-α and lyse cells by release of perforin and granzyme or Fas-mediated lysis
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Describe innate immunity effective control of TB and how immunosuppressors (Infliximab and Etanercept) can cause problems.
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TNF can support anti-TB immunity through the secretion of chemokines, up-regulation of adhesion molecules and the induction of apoptosis of infected Mφ.
- these drugs can reactivate TB |
